Information equipment such as cellular phones is becoming smaller and more highly densified. The trend is likely to continue in an accelerated fashion. Conventionally, in electrical contact spring components for connectors in these instruments, particularly in components which require high strength and demanding bending workability, beryllium copper alloys such as C1720 are mainly used. However, in order to meet a narrower pitch in a future micro electrical contact spring component for connectors, beryllium copper alloys appear to be insufficient in terms of both material strength and electric conductivity. Moreover, beryllium is known as a highly toxic element, and the use of beryllium-free copper alloys is desired for the future in view of the effects on a human body and environment.
To this end, beryllium-free copper alloys having high strength and high electric conductivity have been developed. For example, known are precipitation hardening copper alloys such as Colson alloys and spinodal decomposition copper alloys such as Cu—Ni—Sn based alloys and Cu—Ti based alloys. For precipitation hardening copper alloys, attempts to develop various alloys have been extensively conducted using Cu—Zr, Cu—Cr, Cu—Ag, Cu—Fe and the like as basic compositions (for example, see Japanese Patent No. 2501275, Japanese Patent Laid-Open No. H10-183274, Japanese Patent Laid-Open No. 2005-281757, Japanese Patent Laid-Open No. 2006-299287, Japanese Patent Laid-Open No. 2009-242814). In the case of these precipitation hardening copper alloys, high strength and high electric conductivity can be achieved by adding a strength-improving alloy element to Cu to precipitate a second phase different from the Cu mother phase, and further performing high deformation to finely disperse this phase. Further, spinodal decomposition copper alloys include those in which high strength and good bending workability is achieved by using a Cu—Ni—Sn based alloy having an appropriately controlled structure (for example, see Japanese Patent Laid-Open No. 2009-242895).
However, electrically conductive copper alloys described in Japanese Patent No. 2501275, Japanese Patent Laid-Open No. H10-183274, Japanese Patent Laid-Open No. 2005-281757, Japanese Patent Laid-Open No. 2006-299287, Japanese Patent Laid-Open No. 2009-242814, Japanese Patent Laid-Open No. 2009-242895 require multiple heat treatments such as solution treatment at high temperature in which workability can be improved by primarily re-solid-dissolving alloy elements into the Cu mother phase and aging treatment in which a second phase is appropriately precipitated to obtain a desired property, and accordingly require complex processing procedures to obtain final products. Therefore, disadvantageously, a large amount of thermal energy is required. In order to solve this problem, a Cu—Zr—Ag based copper alloy has been developed which does not require multiple heat treatments, but shows high strength and high conductivity (for example, see Japanese Patent Laid-Open No. 2009-242814).